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Using Fiberglass Patches over Surfboard Fin Box Installations to Increase Strength

Fin boxes are an essential part of any surfboard, as they allow you to attach your fins. However, fin boxes can also be a weak point on a surfboard, as they are often subjected to a lot of stress. This is why it is important to use fiberglass patches to reinforce them.

Why Use Fiberglass Patches?

There are several reasons to use fiberglass patches over surfboard fin box installations:

  • To increase strength: Fiberglass patches can significantly increase the strength of a fin box. This will help to prevent the fin box from breaking or pulling out of the board.
  • To prevent leaks: Fiberglass patches can also help to prevent leaks around the fin box. This is important, as leaks can damage the surfboard's foam core.

How to install fiberglass fin box reinforcement patches:

The fin boxes should already by installed into the surfboard with resin that has cured. The patches will be applied to the board during the bottom fiberglass lamination process.

First download and print out Fiberglass Fin Patch Template below (also designed the right size to fill futures routed pockets if they are too deep)


fin box reinforcement football patch

 Next use the template to cut the patches with 4 oz. or 6 oz. fiberglass. You'll need 1 patch per fin box

Then lay the patches over the fin boxes and center them. At this point you'll roll out or unfold you bottom fiberglass on the board and trim to the outline shape as well as cut the V-notches in the nose and tail areas if required.

Lastly, when saturating the fiberglass cloth with resin during the lamination, let the resin soak into the patches a little longer and make sure to push out any air bubbles that form around the fin box.

Adding fiberglass football reinforcement patches over your fin boxes will greatly increase the impact and torsional strength of your fins and help keep your board from damage.


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